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11 thoughts on “LOP-G”

Where would they go? Prior to any base building there needs to be prospecting. Sending humans would likely be almost as expensive as LOP-G for every site prospected and by the very nature of prospecting, many of those sites would be abandoned. The Trump plan is to do a lot of robotic prospecting on the lunar surface, so details on where a base would be build should be short on details at this stage.

The prospecting missions could build out infrastructure (tugs/landers/communications) that will scale with increasing size of missions.

But can we afford to do both components?

Can we afford to do either? It looks like NASA needs more money either way. I think the most likely outcome is the dual track with Moon/Mars Market/Government that we are on now. IIRC, even if SLS is cancelled, it is only needed for LOP-G because Orion is supposed to act as propulsion for some of the elements. But there is supposed to be a COTS like approach and the propulsion unit is supposed to have several competitors that have to demonstrate their product in space. This means there might be an opening for the “loser” to take on the role of Orion if SLS/Orion is cancelled. Who knows, maybe they would even choose to put the LOP-G in a more useful orbit.

Putting a propellant depot in lunar orbit for missions to Mars makes no sense. It takes more delta-v to go from LEO through TLI and then to enter lunar orbit than it does to launch straight to Mars from LEO. You’d be better off either putting that mission’s depot in LEO or at a LaGrange point.

A propellant depot in lunar orbit for a reusable lunar lander and a reusable Earth to moon to Earth shuttle does make sense.

My point is that launching a Mars mission with a refueling stop in lunar orbit makes no sense from a delta-v perspective. When you combine the delta-v to go from LEO through TLI and then into lunar orbit, then the extra delta-v to accelerate from lunar orbit to go to Mars, it far exceeds what would be necessary to fly straight from LEO on to Mars. For a Mars mission, it’d make more sense to have a depot in LEO. It could be refueled from the Earth or from the moon if mining water from there becomes economically viable.

Why depart for Mars from Lunar Orbit? Because of the propulsion system proposed for the “Deep Space Transport”, a chemical+solar-electric hybrid-rocket system, in principle the same propulsion as the Dawn space probe.

If the DST left from LEO that would add at least a YEAR to the travel time to Mars, compared to leaving from Lunar Orbit. In addition the DST departing from LEO would slowly grind its way up through the Van Allen radiation belt as it spiraled away from Earth, which is bad for the spacecraft as well as any crew aboard.

The only practical reason for the Gateway Station is as support for the DST. And the only practical reason for both the DST and the LOP-G, is for cobbling together a vaguely plausible Mars mission architecture which includes the Orion Spacecraft and Space Launch System.

–For a Mars mission, it’d make more sense to have a depot in LEO. It could be refueled from the Earth or from the moon if mining water from there becomes economically viable.–

For going to a Mars, have depot in Earth and Mars high orbit, so L 1 or 2 of Mars.
And from high orbit, enter trajectory that has low perigee, and accelerate to planetary escape, and get the oberth effect.

I also think that sending crew to Mars in shortest travel time, should be priority. And NASA should carry a lot water for crew use and for radiation sheilding

Part of me is tempted to say, “LOP-G? Oh, please. Just let Musk name it. Then it’ll be the Little Falcon Outpost Block Thingy.” LFOBT!

I think something like a Gateway station could be useful, if it had a meaningful propulsion system and could go to various targets in cis- and translunar space. Repair missions, trips to NEOs that came by, etc.

But I still think for lunar exploration and prospecting, Lunar surface rendezvous would be best. You drop a MoLab type hab/rover on the surface unmanned. Then drop off a crew. When the crew needs to be rotated out, a new ship brings a replacement crew from Earth and picks up the prior one. With resupply and minor repairs on the Moon, the MoLab could cover a lot of ground. If it turns out you need ten of them, deploy ten of them. Unless you’re mining or colonizing, what would you do with a stationary moonbase? And if Bezos wants a lunar industrial park, let him build one. He can afford it.